One of the more perplexing problems encountered by aircraft has been due to air disturbances created by low level wind shear. When wind shear occurs at lower altitudes, such shears have been heretofore difficult to detect with sufficient warning and thus constitute great danger to aircraft.
It has heretofore been suggested that clear air turbulence (which is encountered at higher altitudes) can be detected by detecting temperature gradients existing therein. One such system utilizing detection of infrared or microwave energy from the CO.sub.2 band of the spectrum by use of a radiometric receiver is set forth by R. W. Astheimer in Applied Optics, Vol. 9, pg. 1789 (1970). A method and system for detecting clear air turbulence is also set forth in U.S. Pat. No. 3,696,670. In this patent, it is suggested that detection be based on water vapor anomalies.
One of the better know radiometers for detecting clear air turbulence is the Barnes Model PRT-5 Percision Radiation Thermometer. Clear air turbulence detection is also provided by the apparatus and method described in U.S. patent application Ser. No. 950,943, filed Oct. 13, 1978, now U.S. Pat. No. 4,266,130 by Peter M. Kuhn and entitled "Improved Method and Apparatus for Detecting Clear Air Turbulences." This application discloses a head assembly, processing circuitry and display unit that could be modified and utilized in this invention, as could appropriate structure of the Barnes Model PRT-5 Precision Radiation Thermometer. Atmospheric absorption as a function of frequency and distance in infrared applications is discussed in "Infrared Passbands for Clear Air Turbulence Detection" by Kuhn, Nolt, Stearns and Radostitz in Applied Optics, Vol. 3, No. 4, Oct. 1978.
While apparatus and methods have been heretofore suggested for detecting clear air tubulence, and improvements to such systems have also been heretofore suggested, such systems and/or methods have not been satisfactory in sensing air disturbances created by low level wind shear.
Systems for detection of air disturbances heretofore suggested have also commonly utilized either a single optical filter having a predetermined pass band or a plurality of filters each of which must be selected for a fairly long period of time in order to accomplish the desired end, and improvements in such systems accompanied by improved signal handling capabilities are also thought to be needed.